4 files changed, 48 insertions, 1 deletions

diff --git a/chrome/renderer/render_view.cc b/chrome/renderer/render_view.cc
index 1893e25..e3cbc9f 100644
--- a/chrome/renderer/render_view.cc
+++ b/chrome/renderer/render_view.cc
@@ -443,6 +443,7 @@ void RenderView::OnMessageReceived(const IPC::Message& message) {
     IPC_MESSAGE_HANDLER(ViewMsg_MoveOrResizeStarted, OnMoveOrResizeStarted)
     IPC_MESSAGE_HANDLER(ViewMsg_ExtensionResponse, OnExtensionResponse)
     IPC_MESSAGE_HANDLER(ViewMsg_ClearFocusedNode, OnClearFocusedNode)
+    IPC_MESSAGE_HANDLER(ViewMsg_SetBackground, OnSetBackground)
 
     // Have the super handle all other messages.
     IPC_MESSAGE_UNHANDLED(RenderWidget::OnMessageReceived(message))
@@ -2954,6 +2955,13 @@ void RenderView::OnClearFocusedNode() {
     webview()->ClearFocusedNode();
 }
 
+void RenderView::OnSetBackground(const SkBitmap& background) {
+  if (webview())
+    webview()->SetIsTransparent(!background.empty());
+
+  SetBackground(background);
+}
+
 void RenderView::SendExtensionRequest(const std::string& name,
                                       const std::string& args,
                                       int callback_id,
diff --git a/chrome/renderer/render_view.h b/chrome/renderer/render_view.h
index eb3aa55..505dca0 100644
--- a/chrome/renderer/render_view.h
+++ b/chrome/renderer/render_view.h
@@ -26,6 +26,7 @@
 #include "chrome/renderer/external_host_bindings.h"
 #include "chrome/renderer/external_js_object.h"
 #include "chrome/renderer/render_widget.h"
+#include "skia/include/SkBitmap.h"
 #include "testing/gtest/include/gtest/gtest_prod.h"
 #include "third_party/WebKit/WebKit/chromium/public/WebConsoleMessage.h"
 #include "webkit/glue/dom_serializer_delegate.h"
@@ -52,7 +53,6 @@ class FilePath;
 class GURL;
 class RenderThread;
 class ResourceDispatcher;
-class SkBitmap;
 class WebAccessibilityManager;
 class WebError;
 class WebFrame;
@@ -582,6 +582,10 @@ class RenderView : public RenderWidget,
   // Sends the selection text to the browser.
   void OnRequestSelectionText();
 
+  // Handle message to make the RenderView transparent and render it on top of
+  // a custom background.
+  void OnSetBackground(const SkBitmap& background);
+
   // Prints the page listed in |params|.
   void PrintPage(const ViewMsg_PrintPage_Params& params,
                  const gfx::Size& canvas_size,
diff --git a/chrome/renderer/render_widget.cc b/chrome/renderer/render_widget.cc
index 4cd54c1..23f27da 100644
--- a/chrome/renderer/render_widget.cc
+++ b/chrome/renderer/render_widget.cc
@@ -14,6 +14,7 @@
 #include "chrome/common/transport_dib.h"
 #include "chrome/renderer/render_process.h"
 #include "skia/ext/platform_canvas.h"
+#include "skia/include/SkShader.h"
 #include "third_party/WebKit/WebKit/chromium/public/WebRect.h"
 #include "third_party/WebKit/WebKit/chromium/public/WebScreenInfo.h"
 #include "third_party/WebKit/WebKit/chromium/public/WebSize.h"
@@ -308,6 +309,25 @@ void RenderWidget::ClearFocus() {
 
 void RenderWidget::PaintRect(const gfx::Rect& rect,
                              skia::PlatformCanvas* canvas) {
+
+  // If there is a custom background, tile it.
+  if (!background_.empty()) {
+    canvas->save();
+    
+    SkIRect clipRect = { rect.x(), rect.y(), rect.right(), rect.bottom() };
+    canvas->setClipRegion(SkRegion(clipRect));
+
+    SkPaint paint;
+    SkShader* shader = SkShader::CreateBitmapShader(background_,
+                                                    SkShader::kRepeat_TileMode,
+                                                    SkShader::kRepeat_TileMode);
+    paint.setShader(shader)->unref();
+    paint.setPorterDuffXfermode(SkPorterDuff::kSrcOver_Mode);
+    canvas->drawPaint(paint);
+
+    canvas->restore();
+  }
+
   // Bring the canvas into the coordinate system of the paint rect
   canvas->translate(static_cast<SkScalar>(-rect.x()),
                     static_cast<SkScalar>(-rect.y()));
@@ -675,6 +695,12 @@ void RenderWidget::OnSetTextDirection(int direction) {
   }
 }
 
+void RenderWidget::SetBackground(const SkBitmap& background) {
+  background_ = background;
+  // Generate a full repaint.
+  DidInvalidateRect(webwidget_, gfx::Rect(size_.width(), size_.height()));
+}
+
 bool RenderWidget::next_paint_is_resize_ack() const {
   return ViewHostMsg_PaintRect_Flags::is_resize_ack(next_paint_flags_);
 }
diff --git a/chrome/renderer/render_widget.h b/chrome/renderer/render_widget.h
index 668b4fd..62777e8 100644
--- a/chrome/renderer/render_widget.h
+++ b/chrome/renderer/render_widget.h
@@ -16,6 +16,7 @@
 #include "chrome/common/ipc_channel.h"
 #include "chrome/renderer/render_process.h"
 #include "skia/ext/platform_canvas.h"
+#include "skia/include/SkBitmap.h"
 
 #include "webkit/glue/webwidget_delegate.h"
 #include "webkit/glue/webcursor.h"
@@ -123,6 +124,11 @@ class RenderWidget : public IPC::Channel::Listener,
   // corresponding paint or scroll message is send to the widget host.
   virtual void DidPaint() {}
 
+  // Set the background of the render widget to a bitmap. The bitmap will be
+  // tiled in both directions if it isn't big enough to fill the area. This is
+  // mainly intended to be used in conjuction with WebView::SetIsTransparent().
+  virtual void SetBackground(const SkBitmap& bitmap);
+
   // RenderWidget IPC message handlers
   void OnClose();
   void OnCreatingNewAck(gfx::NativeViewId parent);
@@ -271,6 +277,9 @@ class RenderWidget : public IPC::Channel::Listener,
   // Holds all the needed plugin window moves for a scroll.
   std::vector<WebPluginGeometry> plugin_window_moves_;
 
+  // A custom background for the widget.
+  SkBitmap background_;
+
   DISALLOW_COPY_AND_ASSIGN(RenderWidget);
 };